2 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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26 * $FreeBSD: src/lib/libc/gdtoa/_ldtoa.c,v 1.5 2007/12/09 19:48:57 das Exp $
38 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
39 * except that the floating point argument is passed by reference.
40 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
41 * However, a long double could have a valid exponent of 9999, so we
42 * use INT_MAX in ldtoa() instead.
45 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
49 LDBL_MANT_DIG, /* nbits */
50 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */
51 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */
52 FLT_ROUNDS, /* rounding */
53 #ifdef Sudden_Underflow /* unused, but correct anyway */
62 uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
68 * gdtoa doesn't know anything about the sign of the number, so
69 * if the number is negative, we need to swap rounding modes of
70 * 2 (upwards) and 3 (downwards).
73 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign;
75 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
76 LDBL_TO_ARRAY32(u, bits);
78 switch (fpclassify(u.e)) {
81 #ifdef LDBL_IMPLICIT_NBIT
82 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
83 #endif /* LDBL_IMPLICIT_NBIT */
89 kind = STRTOG_Denormal;
93 kind = STRTOG_Infinite;
102 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
103 if (*decpt == -32768)